1. Field of the Invention
The present invention relates to a thermal analyzer for measuring a physical change of a sample along with its temperature change caused by heating the sample.
2. Description of the Related Art
Conventionally, as a technique of evaluating temperature characteristics of a sample, there has been employed a technique called thermal analysis for measuring a physical change of a sample along with its temperature change caused by heating the sample. The thermal analysis includes all such techniques defined in JIS K 0129:2005 “General rules for thermal analysis,” for measuring physical properties of a measurement target (sample) obtained when the temperature of the sample is controlled based on a program. In general, the thermal analysis is typified by the following five methods: (1) Differential Thermal Analysis (DTA) for detecting a temperature (temperature difference), (2) Differential Scanning calorimetry (DSC) for detecting a heat flow difference, (3) Thermogravimetry (TG) for detecting a mass (weight change), (4) Thermomechanical Analysis (TMA) for detecting mechanical characteristics, and (5) Dynamic Mechanical Analysis (DMA).
For example, as illustrated in FIG. 8, as a thermal analyzer 1000 for performing the above-mentioned thermogravimetry (TG), there is known a thermal analyzer including a furnace tube 9 which is formed into a cylindrical shape and has a gas discharge port 9b which is reduced in diameter and is arranged at a tip end portion 9a thereof, a cylindrical heating furnace 3 which externally surrounds the furnace tube 9, sample holders 41 and 42 which are arranged inside the furnace tube 9 and hold samples S1 and S2, respectively, a measurement chamber 30 which is hermetically connected to a rear end portion 9d of the furnace tube 9, and a weight detector 32 which is arranged inside the measurement chamber 30 and measures weight changes of the samples (see, for example, Japanese Patent Application Laid-open Nos. Hei 11-326249, 2007-232479, and Hei 7-146262). In addition, two support columns 218 extend downward from a lower end of the heating furnace 3, and are connected to a support base 200. Further, a flange part 7 is fixed on the outer side of the rear end portion 9d of the furnace tube 9. A single support column 216 extends downward from a lower end of the flange part 7, and is also connected to the support base 200. The support base 200 and the measurement chamber 30 are placed on a base 10, and the support base 200 is reciprocable by a linear actuator 220 in an axial direction O of the furnace tube 9.
The heating furnace 3 heats the sample holders 41 and 42 from outside the furnace tube 9, and the weight detector 32 may therefore detect weight changes of the samples S1 and S2 along with their temperature changes.
As illustrated in FIG. 9, when setting the samples S1 and S2 onto the respective sample holders 41 and 42 or replacing the samples S1 and S2, the linear actuator 220 advances the support base 200 toward the tip end of the furnace tube 9 (left side of FIG. 9), and also advances the heating furnace 3 and the furnace tube 9 which are fixed to the support base 200. Accordingly, the sample holders 41 and 42 are exposed on the rear end side with respect to the furnace tube 9 so that the samples S1 and S2 can be set or replaced.
By the way, when the above-mentioned thermal analyzer is used, it is possible to detect values of necessary thermophysical properties, but there arises a problem in that the changes of the samples during the thermal analysis cannot visually be observed. This is because the furnace tube 9 is generally made of ceramics such as sintered alumina or a heat-resistant metal such as Inconel (trademark), and the heating furnace 3 covers the furnace tube 9.